U.S. patent number 4,978,104 [Application Number 07/349,766] was granted by the patent office on 1990-12-18 for quick release jack.
Invention is credited to James H. Gipson, Jr..
United States Patent |
4,978,104 |
Gipson, Jr. |
December 18, 1990 |
Quick release jack
Abstract
A quick-release rack and pinion safety jack assembly for
mounting upon the tongue of a conventional trailer. The jack
assembly comprises a vertical support stanchion extending upwardly
from a rotatable caster, a rigid rack, and a weatherproof box-like
gear housing penetrated by the stanchion. A rotatable hand crank is
rotated to move the stanchion relative to the gear housing, to
elevate or lower the trailer. The internal gear assembly comprises
a worm gear driven by the hand crank and a drive gear driven by the
worm which selectively meshes or unmeshes with the rack. The drive
gear is mounted for rotation upon a rigid axle which penetrates
elongated follower slots defined in opposite walls of the gear
housing. The drive gear axle is coupled at its ends by rigid links
rotatably anchored in a pivotal safety lever. The safety lever is
manually deflectable along an arcuate path between a first lock
position and a second released position. As the lever is deflected
downwardly from its "locked" position, the drive gear moves
horizontally along the worm out of engagement with the rack. When
the lever is returned to its lock position, the drive gear rotates
along the worm gear and then meshes with the rack. When the drive
gear is unmeshed from the rack, the stanchion slides freely
relative to the housing for height adjustments without
cranking.
Inventors: |
Gipson, Jr.; James H. (Searcy,
AR) |
Family
ID: |
23373865 |
Appl.
No.: |
07/349,766 |
Filed: |
May 10, 1989 |
Current U.S.
Class: |
254/420; 254/427;
254/97 |
Current CPC
Class: |
B60D
1/66 (20130101); B60S 9/18 (20130101); B66F
3/02 (20130101) |
Current International
Class: |
B60D
1/66 (20060101); B60D 1/00 (20060101); B60S
9/18 (20060101); B60S 9/00 (20060101); B66F
3/02 (20060101); B66F 3/00 (20060101); B60S
009/02 () |
Field of
Search: |
;254/418,420,427,95-97
;269/213,214 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hartman; J. J.
Attorney, Agent or Firm: Carver; Stephen D.
Claims
What is claimed is:
1. A quick-release trailer jack comprising:
an elongated stanchion comprising a base adapted to contact a
supporting surface such as a road;
a rigid rack secured to said stanchion;
a rigid housing slidably mounted upon said stanchion;
clamp means for securing said housing to a trailer tongue;
a drive gear rotatably confined within said housing and normally
meshed with said rack, said drive gear comprising an axle extending
between and captivated by elongated follower slots defined in
opposite sides of said housing;
hand-operated crank means for driving said gear to selectively
displace said stanchion relative to said housing when said gear is
meshed with said rack, said crank means comprising a worm gear
confined within said housing and meshed with said drive gear;
lever means for coupling or uncoupling said drive gear from said
rack, said lever means externally associated with said housing and
comprising a pivot end pivotally coupled to said housing, and a
remote end terminating in a user-accessible handle;
rigid link means for operatively linking said drive gear axle to
said lever means intermediate said pivot end and said handle, said
link means comprising an anchor end pivotally coupled to said gear
axle and a pivot end pivotally coupled to said lever means, and
said link means secured to said lever means between said pivot end
and said handle and displaceable overcenter to normally maintain
said handle in a locked position;
said lever means normally assuming a first position effectuating
locking of said rack, and deflectable to a second position to
quickly release said gear from said rack to disassociate said
stanchion from said housing; and,
whereby pivoting of said lever means by manually deflecting said
handle deflects said link whereby to effectuate movement of said
drive gear toward or away from said rack.
2. The jack as defined in claim 1 wherein deflection of said link
means urges said drive gear into backward rotation along said worm
as it is unmeshed from said rack.
3. The jack as defined in claim 2 wherein said lever means further
comprises externally mounted, removable spring means anchored to
said housing for normally yieldably biasing said lever to said
first position.
4. A quick-release trailer jack comprising:
an elongated stanchion comprising a base adapted to contact a
supporting surface such as a road;
a rigid rack secured to said stanchion;
a rigid housing movably mounted upon said stanchion;
means for securing said jack to a trailer tongue;
a drive gear rotatably confined within said housing and normally
meshed with said rack, said drive gear comprising an axle extending
between and captivated by elongated follower slots defined in
opposite sides of said housing;
crank means for driving said gear to selectively displace said
stanchion relative to said housing when said gear is meshed with
said rack, said crank means comprising a worm gear confined within
said housing and meshed with said drive gear;
lever means for coupling or uncoupling said drive gear from said
rack, said lever means externally associated with said housing and
comprising a pivot end pivotally coupled to said housing, and a
remote end terminating in a user-accessible handle;
cam link means for operatively linking said drive gear axle to said
lever means, said cam link means comprising an anchor end pivotally
coupled to said gear axle and a pivot end pivotally coupled to said
lever means between said pivot end and said handle, said cam link
means normally being yieldably displaced overcenter to normally
maintain said drive gear in a meshed position with said rack;
wherein manual deflection of said handle pivots said lever means to
deflect said cam link means to uncouple said drive gear from said
rack and thus quickly release said stanchion from said housing.
5. The jack as defined in claim 4 wherein deflection of said cam
link means urges said drive gear into backward rotation along said
worm as it is unmeshed from said rack.
6. The jack as defined in claim 5 wherein said lever means further
comprises externally mounted, removable spring means anchored to
said housing for normally biasing said lever means in a position to
mesh said drive gear with said rack.
7. A gear assembly adapted to be retrofitted to the jack post or
stanchion of an existing rack and pinion jack, whereby to enhance
the safe operation thereof, said assembly comprising:
a rigid housing comprising a generally tubular sleeve for engaging
the jack post or stanchion of said existing jack and a rigid,
hollow, box-like gear assembly cover;
a drive gear rotatably confined within said cover for selectively
engaging said rack of said existing jack, said drive gear
comprising an axle extending between elongated follower slots
defined in opposite sides of said cover;
hand-operated crank means for driving said drive gear to
selectively elevate or lower said jack post or stanchion, said
crank means comprising a worm gear inseparably meshed with said
drive gear, said worm gear disposed within said housing generally
perpendicular to said stanchion;
lever means externally associated with said cover for selectively
coupling and uncoupling said stanchion from said housing, said
lever means comprising a pivot end pivotally coupled to said cover
and a remote end terminating in a user-accessible handle;
link means pivotally secured to said lever means between said pivot
end and said handle for coupling said lever means to said drive
gear and driving said axle within said follower slot;
wherein said lever means is normally retained by said link means in
a position in which said link means is displaced overcenter and
said drive gear is meshed with said rack; and,
wherein manual deflection of said lever means causes said link
means to unmesh said drive gear from said rack, and said stanchion
is quickly released form said cover to facilitate raising or
lowering of said jack.
Description
BACKGROUND OF THE INVENTION
The present invention relates broadly to manual rack and pinion
jacks used in conjunction with recreational boat trailers. More
particularly, the present invention relates to a rack and pinion
jack having a safety quick-release mechanism which facilitates
quick and convenient lowering or raising of the jack during use.
Moreover, the present invention relates to a safety quick-release
gear assembly adapted to be retro-fitted to an existing rack and
pinion jack. The invention is believed best classified in U.S.
utility class 254, subclass 97.
It has long been known to employ rack and pinion mechanisms in
jacks. Typical jacks comprise a stanchion adapted to contact a
supporting surface and a stanchion-control housing coupled to the
trailer tongue or bumper of the vehicle to be elevated. Such jacks
generally comprise a lever or crank which engages an internal gear
for vertically moving the stanchion relative to the housing. This
in turn elevates or lowers the trailer tongue relative to the tow
vehicle. Representative prior art rack and pinion jacks are
described by Ketel, U.S. Pat. No. 2,233,135, issued Feb. 25, 1941
and in U.S. Pat. No. 3,466,011, issued to Hewes et al. on Sept. 9,
1969. It is also known in the prior art to provide some form of
safety latching mechanism to prevent accidental disengagement of
the gear assembly from the rack, which might cause an unexpected
and dangerous drop of the trailer.
As will be appreciated by sportsman and hobbyists familiar with the
use of typical prior art jacks, a jack may be raised or lowered
several times during a particular outing. Trailer jacks typically
used with recreational boats are normally semi-permanently mounted
upon the boat trailer tongue and must be raised above ground level
for transport. They must be lowered again when it is desired to
detach the trailer. Typically, before the trailer is disconnected
from the tow vehicle, the jack stanchion will be lowered so that
its base firmly contacts the ground, whereby to maintain the
trailer tongue elevated for subsequent connection or disconnection.
Thus the user is not required to exert extreme effort to lift the
full weight of the trailer into alignment with the hitch. When the
jack must be used with various vehicles of different sizes, it also
may be necessary to crank the jack up or down to align the trailer
tongue with the vehicle.
Thus, one major disadvantage encountered with the use of prior art
jacks known to me is that the user must manually crank the jack up
or down, and the user is not able to selectively disengage the
gears to quickly raise or lower the jack when desired. Thus
lowering the trailer or vehicle after service involves substantial
expenditure of additional effort and time. Manual cranking required
to raise or lower the tongue of the trailer to the necessary height
to accommodate different vehicles has also proven to be too
time-consuming and vexatious.
To overcome this disadvantage, various means for selectively
disengaging the gear from the rack have been suggested in the prior
art. Of particular relevance to the present invention is Weber et
al., U.S. Pat. No. 3,934,852, issued Jan. 27, 1976. The jack
described therein includes a worm gear releasably latched in
position upon a rack and operatively retained by a tiltable hand
crank. When the safety latch is deployed, the user must crank the
jack to effectuate lowering or raising of the trailer. To freely
slide the jack up or down without cranking, the user must manually
depress the latch and simultaneously tilt the crank handle inward
to release the gear from the rack. The main advantage of the prior
art structure is that it greatly reduces the risk of inadvertent
disengagement of the gear, since the user must give considerable
attention and effort to release the safety latch.
However, it is my experience that the release mechanism of the
Weber '852 reference is extremely cumbersome and inconvenient to
use. Moreover, use of the referenced prior art device involves
substantial risk of injury to the user, since the release latch is
positioned proximate the crank handle where the user's hand may be
impacted by the handle when it is released or wedged between the
crank handle and the gear housing. Additionally, it is difficult
for the unskilled user to readily visually discern whether the
safety latch has been released or is still engaged. The user would
not be able to readily detect and promptly replace or repair a
weakened or defective spring in this prior art device, unexpected
accidental release could easily occur. Hence it would be desirable
to provide an improved quick-release mechanism for a safety jack
which may be safely and conveniently deployed by a user and which
is readily monitored in use.
Because a trailer jack is typically a rather costly item, a
purchaser would likely be dissuaded from replacing a relatively
good jack in the interest of enhanced safety. Moreover, it is
unlikely that a user would go to the trouble and expense of
replacing an otherwise sturdy, usable jack due to simple failure of
the safety latch mechanism. In the prior art known to me, no means
are suggested for conveniently replacing a worn or outdated jack
gear mechanism or adding safety devices to existing jacks. It would
thus seem desirable to provide a jack gear safety mechanism which
could be conveniently retrofitted to an existing jack stand.
SUMMARY OF THE INVENTION
The present invention comprises a quick-release rack and pinion
safety jack assembly adapted to be semi-permanently coupled to the
tongue of a conventional recreational boat trailer by a rigid,
adjustable clamp.
The jack assembly comprises a rigid, vertical stanchion preferably
terminating at its lower end in a heavy-duty caster wheel. A
vertical rack mounted upon the stanchion supports meshes with
crank-driven gear assembly. The gear assembly is disposed within a
rigid housing which is penetrated by the jack stanchion. Extending
outwardly from one side of the gear housing is a rotatable hand
crank for manually driving the gear assembly. A spring-biased
safety lever is pivotally coupled to opposite sides of the gear
housing for selectively engaging or releasing the stanchion from
the housing.
The gear assembly comprises a crank-driven worm meshed with a
cooperating drive gear to effectuate vertical movement of the gear
housing upon the rack in response to rotation of the crank handle.
The drive gear is mounted for rotation about a rigid axle which
penetrates elongated follower slots defined within opposite gear
housing walls. The axle is coupled at its ends to rigid links
pivotally coupled to the safety lever. When the safety lever is
moved, corresponding movement of the links and thus the drive gear
results. When the lever is in its first "lock" position, the drive
gear is urged by the links into engagement with the rack, so that
the operator may rotate the crank handle to raise or lower the
jack. When the lever is manually set in its second "release"
position, the drive gear is pushed by the links out of engagement
with the rack, so that the stanchion may be quickly moved
vertically to the desired height without cranking. When the desired
height is attained, the stanchion may then be manually locked into
position again. As the lever is moved back into the locked
position, the links move overcenter, and thus help safely maintain
the lever in the locked position.
The safety lever is biased to its "lock" position by an externally
mounted safety spring anchored upon the gear casing. Substantial
effort is required to pull the lever out of its lock position, so
that the risk of inadvertent release of the lever by a child, for
example, is substantially reduced. Fatigue or failure of the
externally-mounted safety spring may be easily detected. If
necessary, the weakened or damaged spring may be readily replaced
to assure continued safe operation of the jack.
The gear housing may be conveniently retrofitted to an existing
rack and pinion jack which lacks adequate safety and release
mechanisms. After the gear casing of the existing jack is cranked
off the jack post, the present casing may be coaxially slid into
engagement with the rack and cranked into position. It is necessary
merely to drill a handgrip-receptive orifice at the top of the
existing jack post to install the present handle.
Thus it is a broad object of the present invention to provide an
improved rack and pinion type jack for use in conjunction with
trailers or similar vehicles.
A further broad object of the present invention is to provide a
rack and pinion jack which includes an improved quick-release
mechanism.
Still another broad object of the present invention is to provide a
quick-release jack with improved safety features.
Yet another broad object of the present invention is to provide a
quick-release gear mechanism which can be readily retrofitted for
use upon an existing automotive or trailer jack stand.
Another object of the present invention is to provide a jack which
includes external lever means for quickly and conveniently
releasing the gears to permit the user to safely raise or lower the
jack without cranking.
Yet another object of the present invention is to provide a
quick-release jack of the character described which employs
selectively releasable drive gear means.
A further object of the present invention is to provide a
quick-release jack mechanism of the character described which can
be conveniently installed upon an existing jack stand to replace a
worn or outdated gear system.
It is a feature of the present invention that the condition and
deployment of the safety lever mechanism may be readily monitored
by the user.
Another object of the invention is to provide a quick-release jack
which can be safely operated by an inexperienced user, and which
can be easily serviced.
These and other objects and advantages of the present invention,
along with features of novelty appurtenant thereto, will appear or
become apparent in the course of the following descriptive
sections.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following drawings, which form a part of the specification
and which are to be construed in conjunction therewith, and in
which like reference numerals have been employed throughout
wherever possible to indicate like parts in the various views:
FIG. 1 is a pictorial view, illustrating the best mode of my QUICK
RELEASE JACK in use upon a conventional boat trailer;
FIG. 2 is an enlarged, front perspective view of the preferred jack
assembly;
FIG. 3 is a fragmentary, side elevational view of the preferred
gear housing assembly, illustrating the lever in its first locked
position;
FIG. 4 is a fragmentary, side elevational view similar to FIG. 3,
illustrating the lever in its second released position;
FIG. 5 is a sectional view taken generally along line 5--5 of FIG.
3;
FIG. 6 is a sectional view similar to FIG. 5, but illustrating the
gear assembly in its second released position; and,
FIG. 7 is a fragmentary, reduced scale side sectional view similar
to FIG. 3, with portions thereof broken away or omitted for
clarity, and with moved positions illustrated in dashed lines.
DETAILED DESCRIPTION
With initial reference to FIG. 1 of the appended drawings, the best
mode of my improved quick-release jack is broadly designated by the
reference numeral 15. In use jack 15 is clamped to a trailer tongue
16 associated with a conventional trailer 20. Jack 15 comprises a
rigid support stanchion 24 mounted upon a caster assembly 26 which
contacts the ground 27 or similar supporting surface when the load
is supported. A rigid rack 28 is associated with stanchion 24,
which penetrates gear housing 30. A rigid adjustable clamp 35
mounts the jack by securing housing 30 to the trailer tongue 38.
Relative vertical displacements between the stanchion and the
housing are effectuated in response to rotation of manual crank 42,
enabling operator 18 to raise or lower the trailer tongue. A safety
quick-release mechanism, broadly designated by the reference
numeral 48, permits the operator 18 to quickly temporarily release
the stanchion from housing to rapidly adjust the jack without
cranking.
With specific reference now to FIG. 2, the rigid, generally
U-shaped caster mount 50 associated with caster wheel 55 is coupled
for swiveling or rotational movement to the lower end of stanchion
24. An intermediate cylindrical cap fitting 58 firmly engages
stanchion 24 and is secured thereto by conventional pin 59. Rack 28
comprises a multiplicity of gear-engaging teeth and grooves and is
permanently mounted upon stanchion 24 by welds or the like. A
terminal stop 69 associated with the lower end of rack 28 prevents
gear housing 30 from dropping off out of engagement with the rack.
A rigid handle 70 mounted upon the upper end of stanchion 24
facilitates handling of the stanchion and the jack. Mounting clamp
35 comprises a rigid plate 72 permanently welded to housing 30.
Plate 72 is maintained in registered alignment with the cooperating
base plate 74 by bolts 76. Suitable nuts (not shown) conventionally
tighten and secure the apparatus. Plate 72 firmly abuts the upper
surface of the trailer tongue, 16 and base plate 74 is firmed
against the lower surface of the tongue, so that the tongue is
firmly captured between the plates 72 and 74.
With reference to FIGS. 2-4, gear housing 30 comprises a rigid,
elongated, generally tubular sleeve 82 which is coaxially, slidably
fitted upon jack stanchion 24 and a box-like casing 85 which
extends integrally outwardly from sleeve 82 about rack 28. The
casing 85 shields the internal operational mechanism of the jack
from the elements and prevents harmful contact with the operator's
hands. Hand crank 42 comprises a rigid, angular leg 86 and an
integral handgrip 88. Crank 42 extends outwardly from face 89 of
casing 85 for convenient access by the operator 18. Elongated
follower slots 91 are defined in opposing side walls 93 of casing
85 to slidably receive opposing ends of the movable gear axle 152
as described in detail hereinafter.
Safety lever 98 comprises an arcuate handle end 101, and a pair of
integral arms 104 extending upon opposite sides of housing 30 and
terminating in pivot ends coupled to side walls 93 of the casing at
pivot point 105. Lever 98 can pivot along an arcuate path 107 (FIG.
7) between a first, "locked" position at point 107A (FIG. 3) and a
second "released" position at point 107B (FIG. 4). The lever thus
controls the mechanical interconnection between the stanchion and
the housing, as will hereinafter be described.
Lever 98 is preferably biased by an external spring 110 secured to
orifice 112 defined in lever arm 104. The spring opposite end is
secured by a fastener 115 associated with casing 85. Because spring
110 is externally mounted, it is readily visible and its condition
can be easily monitored by the operator 18. If the spring 110
becomes distended or worn, it can be quickly and easily removed and
replaced with a new spring. Thus, the risk of mechanical failure of
the safety lever is substantially reduced.
With additional reference now directed to FIGS. 5-7, the jack 15 is
driven by a gear assembly, broadly designated by the reference
numeral 120, which is enclosed within casing 85. A drive gear 138
is the most important element of the gear assembly. It is switched
into and out of contact with the rack 28 by the lever 98 to
facilitate release. A rotatable worm gear 124 is meshed with drive
gear 138. Worm gear 124 is splined to a rigid drive shaft 128.
Shaft 128 penetrates casing face 89 and terminates in crank 42,
which is secured thereto by a nut 131 or similar fastener. When the
crank is manually rotated by operator 18, the worm gear rotates
drive gear 138. Drive gear 138 comprises a hub 141 and a plurality
of teeth separated by grooves. Thus rotation of the worm gear
results in vertical rotation of drive gear 138 along rack 28 as
indicated by arrow 149. When the drive gear is meshed with the
rack, movement between the stanchion and the housing results.
Drive gear 138 is mounted for rotation upon a rigid axle 152. Axle
152 traverses the interior of casing 85 and penetrates the follower
slots 91 defined through opposite casing walls 93. Axle 152 is
rotatably captured at its ends by elongated, rigid links 156
screw-mounted by fasteners 158. Links 156 are rotatably anchored
upon arms 104 at a pivot point 160 adjacent the safety lever pivot
point 105. Links 156 are sandwiched between arms 104 and casing
side walls 93. Links 156 move overcenter, pivoting along an arc
opposite arcuate path 107 in response to operator-selective
deflection of lever 98. Thus, deflection of links 156 results in
straight-line, horizontal movement of drive gear axle 152 within
follower slots 91 along a path indicated by arrow 159, which in
turn drives drive gear 138 horizontally along worm 124.
As best illustrated in FIGS. 3 and 5, when safety lever 98 is in
its first, raised "locked" position, links 156 lie roughly parallel
with lever arms 104 and urge drive gear axle 152 rearwardly in the
direction of sleeve 82. As drive gear axle moves horizontally
toward the rearward limit of follower slot 91, drive gear 183
rotates rearwardly along worm 124 until gear 183 comes into
engagement with rack 28. In the locked position, movement of the
gear housing upon the stanchion may only be effectuated by manual
rotation of the crank handle.
As best viewed in FIGS. 4 and 6, when lever 98 is lowered links 156
move overcenter into roughly perpendicular orientation relative to
lever arms 104. Links 156 thus pivot to drive the drive gear axle
152 forward within follower slot 91 generally in the direction of
crank 42. As the drive gear axle moves horizontally toward the
forward limit of follower slot 91, the drive gear rotates
horizontally forward along worm 124, until the drive gear is drawn
out of engagement with rack 28. Movement of the jack is thus
virtually unrestricted by drive gear 138, and the jack housing 30
may be safely and quickly slid vertically coaxially along stanchion
24 to the desired position without cranking. This facilitates rapid
positioning of the jack at the desired elevation.
When it is desired, for example, to quickly raise the jack off the
ground for transport as shown in FIG. 1, operator 18 may grasp
handle 70 upon stanchion 24 with one hand. With the other hand,
operator 18 pushes safety lever 98 downward to the release
position, and slides gear housing into the desired position upon
the stanchion. It will be appreciated that since both hands are
required to effectuate the release, the risk of inadvertent
tripping of the assembly is greatly reduced. Additionally, it is
noted that the operator's hands are positioned out of reach of the
handcrank, whereby the risk of injury from inadvertent contact
therewith is eliminated. Once the jack is thus properly positioned,
lever 98 may be manually raised to safely re-lock the gear housing
into the desired position.
Spring 110 biases lever 98 in its raised "locked" position, whereby
substantial effort is required to pull the lever out of its lock
position to release the jack for slidable adjustment. Hence, the
risk of inadvertent release of the lever by a child, for example,
is substantially reduced. Moreover, once the desired position is
reached, spring 110 acts to assist quick and easy return of the
lever back to the safety lock position.
It will be appreciated that, due to the expense involved, the
typical consumer would not invest the substantial amount of money
required to replace a jack merely to gain the advantage of improved
safety. The present gear housing is so constructed that it may be
quickly and conveniently retrofitted onto the stanchion of an
existing rack and pinion jack.
To install the housing, operator 18 must disconnect the caster or
support base from the existing jack so that the old gear housing
may be cranked down and removed from the jackpost. The present gear
housing may be slidably installed onto the rack by positioning the
safety lever in the release position to prevent damage to the drive
gear by contact with the rack during installation. Once the housing
is properly positioned so that the gears intermesh, the safety
lever may be raised to its lock position. The operator must then
drill an orifice through the top of the existing jackpost to mount
the present handle, which may be quickly anchored thereto upon a
suitable, rigid pin.
From the foregoing, it will be seen that this invention is one well
adapted to obtain all the ends and objects herein set forth,
together with other advantages which are inherent to the
structure.
It will be understood that certain features and subcombinations are
of utility and may be employed without reference to other features
and subcombinations. This is contemplated by and is within the
scope of the claims.
As many possible embodiments may be made of the invention without
departing from the scope thereof, it is to be understood that all
matter herein set forth or shown in the accompanying drawings is to
be interpreted as illustrative and not in a limiting sense.
* * * * *